SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '311f33e0b368d6b33806fa4fbcb5668d6cb80b9be1c2910ad565425b967f97ff' 
  AND token = 'r0CgBIotvZz6l2mPGENDv2zgD+9BwfE9jgYNHl5OhXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}